1. Field of the Invention
The present invention relates generally to voltage converters and, more particularly, to coupled-inductor voltage converters.
2. Description of the Related Art
Lightweight, reliable, and efficient power supplies are essential in many modern electronic systems. Linear power converters, based on the use of voltage or current dividers, are often used to provide high-quality output voltages. These converters, however, are inefficient because many of their elements operate in their active (linear) modes. Accordingly, their use is typically restricted to applications that have low power demands.
In contrast, switching converters provide output voltages with high efficiency because their operational states generally comprise a) a low voltage across a switch in an on state, and b) zero current through a switch in an off state. Switching converter components can be arranged to provide an output voltage that is lower than the input voltage (a buck converter) or to provide an output voltage that is higher than the input voltage (a boost converter).
The switches of these converters are often realized with power metal-oxide-semiconductor field effect transistors (MOSFETs) that are generally switched at high frequencies in order to reduce the size of other regulator components (e.g., filter inductors and capacitors). In order to provide a desired voltage, the transistor switches are often controlled with a pulse-width modulation feedback system.
Switching converters have become widely used in a variety of electronic devices (e.g., cell phones, digital cameras, portable computers, computer peripherals, network cards, routers, and set-top boxes) and, accordingly, there is a considerable demand for further improvements in their efficiency.